1. Field of the Invention
The present invention relates to an apparatus for inspecting light emitting diode (LED) packages capable of inspecting LEDs to determine whether or not the LEDs are defective and discarding an LED if the LED is defective.
2. Description of the Related Art
A light emitting diode (LED) generates minority carriers (electrons or holes) injected by using a p-n junction structure and emits light according to electron-hole recombination. Namely, when a forward voltage is applied to semiconductor of a particular element, electrons and holes are moved to be recombined through a junction of a positive electrode and a negative electrode, and in this case, a smaller amount of energy is generated than that generated when the electrons and holes are separated, so light is emitted due to the difference between the generated energies.
In line with recent improvements in the luminous efficiency of the LED, the applications thereof extends from an initial LED for displaying signals to an LED for a backlight unit (BLU) for mobile phones, or for an LED to be used as a light source or for the illumination of a flat panel display device such as a liquid crystal display (LCD). The reason for this is because the LED has low power consumption and has a long life span as compared with light bulbs and fluorescent lamps used as conventional sources of illumination.
The LED may be generally fabricated as an LED package. In general, an LED package includes an LED chip, a body on which the LED chip is mounted, and a fluorescent material-containing resin part, such as fluorescent silicon, covering the LED chip at an upper portion of the body. The LED package may further include a Zener diode beside the LED chip.
The LED chip is fabricated by growing semiconductor layers, each having a different conductive type and an active layer for activating light emission between the semiconductor layers, and forming electrodes on the respective semiconductor layers. The LED chip and the Zener diode are electrically connected to a lead frame through wire bonding.
When fluorescent silicon is charged at an upper portion of the LED chip and the Zener diode, if the fluorescent silicon is scantly charged, the internal bonding wire may be exposed and cut off due to heat generation. Conversely, in the case that the fluorescent silicon is excessively charged, when a module is assembled later, assembling may be impossible and a diffusion angle of light may be larger than a set numerical value. Thus, in fabricating the LED package, a process of inspecting a state of a charge in the fluorescent silicon is required.
In the related art, in most cases, an operator inspects the charged state of the fluorescent silicon with his naked eyes and sorts out a defective LED package to discard it. Thus, a skilled operator is required and the manual operation thereof limits an improvement of productivity.